Our long-term goal is to establish the origin of the reduced activity of 5'-AMP aminohydrolase and pyruvate kinase in dystrophic chicken breast muscle. To date we have convincing evidence that 5'-AMP aminohydrolase from line 307, the early onset line, is different from that obtained from normal muscle. Evidence includes an altered isoelectric point and an altered carbohydrate content. Our primary immediate goal is to measure the rates of synthesis and degradation of these enzymes.